Speaking on the condition of anonymity, he told the New York Times that about a dozen people had been arrested in the raid in Muzaffarabad, the capital of Pakistani-administered Kashmir.
American Embassy officials here could not verify the claim independently.
The operation on Sunday appeared to be Pakistan"s first concrete response to the demands from India and the United States to take action against the militants suspected in the attacks, which have raised tensions between the nuclear-armed neighbors to their highest point in years.
American intelligence and counter-terrorism officials told The New York Times that Pakistan"s Inter-Services Intelligence, continues to back the group, even after 9/11, when the Pakistani government pledged to sever its ties with militant groups.
While investigators and intelligence officials say there is no hard evidence linking Pakistan"s spy agency to the Mumbai attacks, they have pointed to Lashkar as the likely culprit.
Islamabad has resisted the notion that Pakistani citizens may have been involved in the Mumbai attacks, and it has so far refused to hand over 20 criminal and terrorist suspects long demanded by the Indians.
Counter-terrorism experts familiar with the behavior of the Pakistani security services said there was a need by Pakistan to be seen to be doing something to alleviate the American and Indian pressure, as well as to avert the possibility of an Indian military strike.
Still, the effectiveness of that action might be less than India or the United States would like, they said.
A senior Pakistani official said the operation was part of a gradual effort to bring the militants under control.
“Pakistan will do it at its own pace, not at gunpoint," said a senior politician in the Pakistan Peoples Party, who declined to be named because he was not authorized to speak.
“The street is upset. For that reason, the government could not move too harshly against Lashkar-e-Taiba," he said.